Anthony Zurcher

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The latest Washington parlour game is trying to determine whether or not special counsel Robert Mueller is currently investigating Donald Trump for obstruction of justice in the Russia election meddling inquiry.

Mr Trump's lawyers have denied it. The president himself seemed to confirm it. Mr Mueller isn't talking. All this speculation misses the bigger question, however. What happens if Mr Mueller not only is looking into possible criminal misdeeds by the president, but he ends up finding them?

Such a prospect opens a legal Pandora's box - but it's one Mr Mueller should probably be pondering. Here are some possible what-next scenarios if that smoking gun (or guns) turns up.

A report to Congress

The traditional means of addressing presidential criminality - if "traditional" is the right word, given that it's a path explored only three times in US history - is through impeachment proceedings in the House of Representatives followed by trial in the US Senate.

Impeachment requires a simple majority vote, while it takes a two-thirds majority in the Senate to approve removal. It is, as is frequently noted, a political act first and foremost, where the grounds for action are essentially whatever Congress decides.

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Congressman Joe Barton of Texas and Chuck Fleischmann of Tennessee walked down the road near a baseball field in Alexandria, Virginia, in stunned silence. Mr Barton's two sons were alongside, the younger still carrying his glove and staring intently at the ground in front of him.

Less than an hour earlier, they had been part of the chaotic scene when a gunman opened fire on Republican politicians, staff and friends who were practising baseball. Congressman Steve Scalise, the third-ranking member of the party's House of Representatives leadership team, was seriously wounded, as were several others.

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The glimpse Jeff Sessions offered into the controversies bedevilling the Trump administration came through a glass, darkly.

During his testimony before the Senate committee investigating Russian meddling in the 2016 presidential campaign, he was often evasive. His accounting of details was uncertain, littered with "I don't recalls" and "I have no recollections".

US Attorney General Jeff Sessions' appearance before the Senate Intelligence Committee on Tuesday is the biggest thing to hit Washington since, uh, last week.

OK, so the sequel to the James Comey hearing doesn't have the same build-up as the original, but that doesn't mean that there won't be fireworks - or that the proceedings can't cause new headaches for the Trump administration.

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The Senate testimony of ex-FBI boss James Comey dominated the headlines last week, but the latest announcements from Robert Mueller's special counsel investigation could be a more ominous indication of trouble on the horizon for the Trump administration.

Mr Mueller, who was tasked by Deputy Attorney General Rod Rosenstein with overseeing the Justice Department's inquiry into possible ties between the Trump presidential campaign and Russian operatives, is staffing up his office - and bringing in some prosecutorial heavy-hitters.

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James Comey didn't bury Donald Trump in his Senate testimony, but he dug a Trump-sized hole in the ground.

While the former FBI director danced around what, if anything, the ongoing investigation into possible Trump campaign Russia ties has found, he was much more forthcoming about his relations with the president, before and after his dismissal - and how they made him feel.

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When former FBI Director James Comey testifies on Thursday before a Senate committee for the first time since being fired by President Donald Trump in May, it quite possibly will be the biggest piece of political theatre the nation's capital has seen in a generation.

The city is going to grind to a halt to observe the spectacle. Local bars are opening early to host viewing parties. Democrats and Republicans will be united in rapt attention as the former director has his first opportunity to publicly give his account of his interactions with the president and the circumstances of his dismissal.

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The London Bridge attacks set Donald Trump off on an extended Twitter rant over the past few days, reviving his calls for sweeping immigration action and renewing old feuds with Democrats, gun-control advocates and even the mayor of London.

While White House advisor Kellyanne Conway recently complained that the media have an "obsession with covering everything he says on Twitter and very little of what he does as president", Mr Trump is the pot-stirrer-in-chief, who has the power to drive debate and shape events.

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For a speech about whether the US should remain a party to the Paris climate accord, Donald Trump's Rose Garden address on Thursday didn't have a whole lot of discussion about, you know, the climate.

There was plenty of talk about jobs and the US economy. He offered more than a few expressions of concern over whether other nations were being given an unfair advantage over the US. And then there was that lengthy opening plug for his presidential accomplishments that had nothing to do with the environment whatsoever.

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In the end the collected pressure from environmentalists, diplomats, major US corporations, foreign leaders, Mitt Romney, Leonardo Di Caprio and Ivanka Trump wasn't enough. The US is charting its own course, leaving the international community to fend for itself.

The implications for that community, and the role of US leadership in it, will be the subject of considerable discussion in the days ahead. This decision was not made with international affairs in mind, however. It was one of domestic politics, pure and simple.